A 70-year-old man with hypertension and hypercholesterolemia is presenting for partial colectomy. Based on an observational study investigating cardiovascular drug exposure and postoperative mortality in elderly hypertensive patients presenting for surgery, which of the following medications taken preoperatively is most likely to increase mortality?
(C) Thiazide diuretics
(D) Angiotensin-converting enzyme inhibitors
The role of perioperative β-blockers has changed throughout the years. Once considered protective against cardiovascular complications, more recent evidence suggests their use – especially in low-risk patients – may cause more harm than good. Specifically, the Perioperative Ischemic Evaluation (POISE) study, a large randomized controlled trial, demonstrated that β-blocker administration prior to noncardiac surgery increased the risk of stroke, sepsis and death. The authors of a recent cohort study sought to evaluate the effect of perioperative β-blocker use in elderly hypertensive patients.
Data from the U.K. Clinical Practice Research Datalink were used to identify patients 65 years and older who had undergone noncardiac surgery between January 2004 and December 2013. From this database, information on pre-operative cardiovascular medication use was extracted. The main outcome was death within 30 days of surgery. Patients were categorized into three blood pressure (BP) thresholds based on most recent preoperative systolic BP reading: hypotensive (<120 mm Hg), normotensive (120-139 mm Hg) or hypertensive (≥140 mm Hg). Propensity scores were used to match patients based on exposure to six cardiovascular drug classes: statins, β-blockers, calcium-channel blockers, renin-angiotensin system (RAS) inhibitors, thiazide diuretics and loop diuretics. Conditional logistic regression was used to evaluate the association of drug exposure to mortality. Covariates included in the model were age, sex, α2-agonists, aspirin, other antiplatelet agents, atrial fibrillation, unstable angina, valvular heart disease, myocardial infarction, cerebro-vascular disease, peripheral vascular disease, chronic pulmonary disease (including asthma), heart failure, diabetes mellitus, renal disease, liver disease, cancer, body mass index, smoking status, alcohol use and socioeconomic status.
More than 84,000 patients were included in the study. Approximately half of these patients were hypertensive. Among all patients, 25.8% were on no cardiovascular drugs, 18.4% were on one drug, and 15.8% were on two drugs. A total of 14.4% of patients were on a β-blocker. Atenolol was the most commonly prescribed β-blocker followed by bisoprolol.
After adjusting for relevant confounders, the authors found that preoperative β-blocker use was associated with increased odds of postoperative mortality in patients with systolic hypertension (adjusted odds ratio [aOR], 1.92; 95% CI, 1.05-3.51). This association remained when patients with a history of either myocardial infarction or heart failure were excluded. Conversely, the preoperative use of statins (aOR, 0.35; 95% CI, 0.17-0.75) or thiazide diuretics (aOR, 0.28; 95% CI, 0.10-0.78) was found to exert a protective effect and decrease the odds of postoperative mortality. No association was found between preoperative calcium-channel blocker, angiotensin-converting enzyme inhibitor, or loop diuretic use and postoperative mortality.
An important limitation of this study is that data on administration of β-blockers intra- and postoperatively were not evaluated; therefore, it is uncertain whether the results observed were affected by perioperative β-blocker withdrawal. Regardless, this study adds further support to the notion that preoperative β-blocker use may be associated with more harm than good.
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